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Sub 505 Level|   Statistics and Sets Problems|                                       
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Video solution from Quant Reasoning:
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which is the level of the question? 500? tks a lot :)
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which is the level of the question? 500? tks a lot :)

I'd say it's ~600.

P.S. You can see the difficulty level of a question in the first post where the tags are (TAGS: Difficulty: 600-700 Level).
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Attachment:
Number line.png
On the number line above, p, q, r, s, and t are five consecutive even integers in increasing order. What is the average (arithmetic mean) of these five integers?

(1) q + s =24
(2) The average (arithmetic mean) of q and r is 11.

Ans. : Let p=x, q=x+2, r=x+4 , s=x+6, t=x+8 to find the mean we need to find x.
From statement 1 , we get 2x+8=24
From statement 2 we get x+3=11
Therefore the answer is (D).
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My understanding of consecutive integers, is that they are separated by only 1, i.e. 3, 4, 5, 6, 7, 8

I was able to find the first statement sufficient, but not the second, mainly because the answer uses the formula p + (p+2) +....

Why is 2 being added to P?
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My understanding of consecutive integers, is that they are separated by only 1, i.e. 3, 4, 5, 6, 7, 8

I was able to find the first statement sufficient, but not the second, mainly because the answer uses the formula p + (p+2) +....

Why is 2 being added to P?

We are not told that p, q, r, s, and t are consecutive integers. We are given that p, q, r, s, and t are five consecutive EVEN integers. For example 2, 4, 6, 8, 10.
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They are basically giving us some equation in disguise.

1. q+s=24 but for a fact set we know that the leap between q and s is 4 and this translates into an equation that subtracted gives us the value of q from which we can calculate the average.
2. q+r=22 same old story, the leap between q and r this time is 2 units. r-q=2 subtract it from the given equation and you are done you got one value, the remaining values follow logically.

D.
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Attachment:
Number line.png
On the number line above, p, q, r, s, and t are five consecutive even integers in increasing order. What is the average (arithmetic mean) of these five integers?

(1) q + s =24
(2) The average (arithmetic mean) of q and r is 11.

Solution:

Recall that in a set of evenly spaced numbers, mean is equal to the median. Thus, the average of these five integers is equal to r.

Statement One Alone:

q + s = 24

Notice that the set consisting of q, r and s is also evenly spaced; therefore the mean of this set is also equal to the median, which is r. Recall that for a set of evenly spaced numbers, the mean is equal to the average of the greatest and the smallest elements; thus r = mean = (q + s)/2 = 24/2 = 12.

Statement one alone is sufficient.

Statement Two Alone:

The average of q and r is 11.

Since (q + r)/2 = 11, q + r = 22. Since q and r are consecutive even integers, q = r - 2. Then, (r - 2) + r = 2r - 2 = 22. Solving the equation, we get r = 12.

Statement two alone is sufficient.

Answer: D
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Attachment:
Number line.png
On the number line above, p, q, r, s, and t are five consecutive even integers in increasing order. What is the average (arithmetic mean) of these five integers?

(1) q + s =24
(2) The average (arithmetic mean) of q and r is 11.


Given:
CONSECUTIVE EVEN INTEGERS
p=2n
q=2n+2
r=2n+4
s=2n+6
t=2n+8

p<q<r<s<t

Mean= (2n+2n+2+2n+4+2n+6+2n+8)/5
= (10n+20)/5
=10(n+2)/5
=2(n+2)


(1) q+s=24
2n+2+2n+6=24
One variable thus can be solved.

Sufficient.

AD

(2) Mean= (2n+2+2n+4)/2

One variable thus can be solved.

D
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STatement 1 no. of terms is 5 so the center term i.e r will be the avg as the series is an Arithmetic progression
so it can be found by (q +s)/2 = 12.

Statement 2 : given :- (q + r) / 2 = 11.
also q = r-2 (as all are even consecutive integers in a series.)
So again the avg can be found out.

Answer D
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1) q+s=24
p,q,r,s,t

s-q= 4 and s+q =24. add them. s=14 and series will be 8,10,12,14,16 and mean will be 12. sufficient A/D can be answer

2) mean of q and r is 11, q+r=22.
r+q=22 , r-q =2 add them r=12, and series will be again same and same answer as above therefore sufficient

D is answer
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Attachment:
Number line.png
On the number line above, p, q, r, s, and t are five consecutive even integers in increasing order. What is the average (arithmetic mean) of these five integers?

(1) q + s =24

As we know that r is the median of q and s, and r is also the median of p,q,r,s, and t. Hence, if we know the value of r we should be able to answer the question.

q + s = 24

Midpoint = 24/2 = 12 = r

Hence, (1) ===== is SUFFICIENT

(2) The average (arithmetic mean) of q and r is 11

q = r - 2

r - 2 + r = 11 * 2

2r = 24

r = 12

Hence, (2) ===== is SUFFICIENT

Hence, Answer is D

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Updated - Thank you for bring it up.
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Attachment:
Number line.png
On the number line above, p, q, r, s, and t are five consecutive even integers in increasing order. What is the average (arithmetic mean) of these five integers?

(1) q + s =24
(2) The average (arithmetic mean) of q and r is 11.

P, Q, R, S, and T are consecutive even integer. Let p = X, So,
P = X
Q=X+2
R=X+2+2=X+4
S= X+4+2=X+6
T=X+6+2=X+8

(1) X+2+X+6=24 Sufficient to the value of X; Sufficient.

(2) [(x+2+x+40/2]=11; We will get the value of x from this equation. Sufficient.

Answer D.
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Forget the conventional way to solve DS questions.

We will solve this DS question using the variable approach.

DS question with 1 variable: Let the original condition in a DS question contain 1 variable. Now, 1 variable would generally require 1 equation for us to be able to solve for the value of the variable.

We know that each condition would usually give us an equation, and Since we need 1 equation to match the numbers of variables and equations in the original condition, the logical answer is D.

To master the Variable Approach, visit https://www.mathrevolution.com and check our lessons and proven techniques to score high in DS questions.

Let’s apply the 3 steps suggested previously. [Watch lessons on our website to master these 3 steps]

Step 1 of the Variable Approach: Modifying and rechecking the original condition and the question. We have to find an average of five integers.

=> p, q, r, s and t are consecutive even integers.Therefore,

=> q = p + 2, r = p + 4, s = p + 6 and t = p + 8.

=> We need value of \(\frac{(p + p + 2 + p + 4 + p + 6 + p + 8) }{ 5}\) OR \(\frac{(p + 20)}{5}\)

Second and the third step of Variable Approach: From the original condition, we have 1 variable (p).To match the number of variables with the number of equations, we need 1 equation. Since conditions (1) and (2) will provide 1 equation each, D would most likely be the answer.

Let’s take look at each condition.

Condition(1) tells us that the q + s = 24.

=> p + 2 + p + 6 = 24

=> 2p = 16 or p = 8

=> Average: \(\frac{(8 + 20) }{ 5}\) = 5.6

Since the answer is unique, condition(1) alone is sufficient by CMT 2.


Condition(2) tells us that the average mean of 'q' and 'r' is 11 .

=> q + r = 11 * 2 = 22

=> p + 2 + p + 4 = 22

=> 2p = 16 or p = 8

=> Average: \(\frac{(8 + 20) }{ 5}\) = 5.6

Since the answer is unique, condition(2) alone is sufficient by CMT 2.


Each condition alone is sufficient.

So, C is the correct answer.

Answer: C

Since, it is a key question[Statistics], if value of Con(1) = value of Con(2), answer is D
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Attachment:
Number line.png
On the number line above, p, q, r, s, and t are five consecutive even integers in increasing order. What is the average (arithmetic mean) of these five integers?

(1) q + s =24
(2) The average (arithmetic mean) of q and r is 11.

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Answer: Option D

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